Process of electric heating.



No. 757,618. PATBNTED APR.19,1904.

W. s. HORRY. PROCESS 015 ELECTRIC HEATING.

APPLICATION FILED APR. 5, 1902. N0 MODEL. I 2 SHEETS-818E121 1.

No. 757,618. PATENTED APR. 19, 1904.

' W. S. HURRY.

PROCESS OF ELECTRIC HEATING.

APPLIOATIOH FILED APB. 5, 1902. w 110 110mm. 2 SHEETS-SHEET 2.

UNITED STATES Patented April 19, 1904.'

PATENT OFFICE.

WVILLIAM SMITH HORRY, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO UNION CARBIDE COMPANY, OF NIAGARA FALLS, NEWV YORK, A COR- PORATION or VIRGINIA.

PROCESS OF ELECTRTOHEATING.

SPECIFICATION, formingpart of Letters Patent No. 757,618, dated April 19, 1904.

Application filed April 5, 1902. Serial No. 101,505. (No specimens-l To all 10/1/0711, it natty concern:

Be it known that I, WILLIAM SMITH HoRRY, a subject of the King of Great Britain, residing at Niagara Falls, in the county of Niagara and State of New York, have invented a certain new and useful Process of Electric Heating, of which the following is a specification.

This invention relates to the art of electrically heating a body of conducting material, especially a mixture of a metallic compound and a reducing agent, and, specifically, a mixture of lime and carbon for the production of calcium carbid. The process contemplates the use of a polyphase alternating current, preferably one with many phases, the paths of the several phasesbeing so distributed within the conducting-body as to effect an even heating thereof. The process is carried out by causing different phases of the current to simultaneously flow along paths-which cross each other through the body and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase. The body to be heated is preferably a circular disk, the active terminals of the source of polyphase current being placed substantially in contact with the body at various equidistant points around its periphery and the terminals between which the maximum potential difference is set up being arranged at opposite ends of a diameter of the circular disk, this diameter successively shifting between successive pairs of opposite terminals, following the shifting phases in the windings of the dynamo or other source of current.

The invention will be more easily understood by reference to the accompanying drawings, in which Figure 1 is a diagram illustrating the heating of a circular disk by a current of six phases having twelve active terminals arranged in contact with the edge of the disk. Fig. 2 is a horizontal section of a square electric furnace employing a current of two phases, the current being distributed to the electrodes by transformers whose windings are shown in diagram; and Figs. 3 and 4 are a vertical axial section and ahorizonta'l section, respectively,

of an electric furnace designed for the commercial utilization of the process.

The circular body to be heated (shown in Fig. 1) may be a disk of metal or a metallic crucible, but is more especially a layer of calcium carbid or of carbid-forming materials, such as exists in the lower part of the furnace (shown in Figs. 3, 4) when in normal working operation. The terminals of the source of polyphase current, here shown as twelve in 7 number, are placed substantially in contact .with the edge of the disk at equidistant points,

numbered 1 to 12. The source of current may be a dynamo having a fixed external armature consisting of a circular Gramme ring with continuous winding, leads being taken out from the winding at twelve equidistant points to the several terminals in contact with the disk. Within the armature is a bipolar revolving field. The maximum electromotive force of this generator is assumed to be two hundred Volts and the current carried by the maximum volts to be passing between the terminals l and7of Fig. 1, fallof potential in the dynamo and conductors being neglected. A number of currents will then simultaneously flow through the disk along paths indicated by the broken lines, the potential difference between the terminals at the end of each path of current-flow being indicated by the numerals applied to the several lines. It will thus be seen that the electromotive force tending to drive a current along each path substantially corresponds to the resistance of that path, thus giving an equal current along every line. As the field revolves within the dynamo. the phase of maximum electromotive force shifts from terminals 1 7 to 2 8 and then to 3 9, and so on. It will thus be seen that the disk is heated to a practically uniform temperature throughout.

Figs. 3 and 4 show a furnace for the use of this process of heating in the production of calcium carbid designed to receive a current of two thousand kilowatts or more. The furnace comprises an annular stack 21, of refractory material, such as fire-brick, having at its upper end a suitable mechanism 22 for introdueing raw material and preventing the es cape of gas, here shown as a bell and hopper. Through the side of the stack, near its upper end, passes a flue 23 for withdrawing the waste gases. Near the lower portion of the stack are arranged one or more horizontal series of radial electrodes 24:, here shown as cylindrical carbon rods passing adjustably through the sides of the stack. Each horizontal series comprises twenty-four electrodes, each connected to one terminal of a dynamo or transformer giving a current of twelve phases. A tap-opening 25 for the molten carbid extends through one side of the stack near its lower end. This tap-opening, however, may be closed and the carbid maintained at or above the level of the electrodes, in which case it can be tapped off through one of the openings which receives an electrode upon withdrawing the latter, such as the lower right-hand electrode Qet in Fig. 3. In employing this furnace to carry out the process of producing calcium carbid an initial charge consisting of lime and carbon is fed in through the top of the furnace. This charge may be the well-known one containing large pieces of coke, which lie in contact with each other at various points, and thereby afford direct paths for the flow of current, the lime being distributed in the interstices between pieces of coke. If the normal charge, however, consists of a non-conducting mixture of coke and lime, the furnace must be first put in operation by the use of a conducting charge or by ubllQIWlSG providing initial paths for the flow U1 current. As soon, however, as current asses through a conducting body in the lower part of the furnace the temperature soon rises to a point where the charge above is preheated by conduction and radiation and by the waste gases rising from the zone of reduction to a temperature which will enable it to act as a resistance-conductor when it descends into the paths of current-flow. In normal working condition the body of material between the eleetrodes may consist of molten or partly-molten carbid or of incandescent but um'educed material, or in part of both. The process is carried out in a continuous manner by tapping out the molten carbid and supplying fresh material, as required. As the current density for each electrode cannot be carried above a certain limit, the total energy which can be em- 5 ployed in heating the charge depends on the number of electrodes, which may be increased, as desired, either by arranging a greater number in the same horizontal series or by using any desired number of superposed horizontal series. The use of a large number of electrodes is a desirable feature of this process of heating by polyphase currents, since it permits the use of relatively small electrodes without unduly heating them or their ternii- 1 nal connections. The use of a current of a l large number of phases avoids certain dilliculties incident to a singlephase current. Practically the maximum voltage of the generator is always maintained between one pair of electrodes, the working current thus being the maximum current of the generatorinstead of varying from zero to a maximum. For the same reason the total cross-section of the electrodes may be smaller than for a furnace of the same capacity using single-phase current, effecting a saving in this respect of about thirty per cent, by weight. Any electrode may also be removed and replaced by another without noticeably interfering with the operation of the furnace. It is evident that by this process the advantages of the direct current are retained without subjecting the furnace charge to the electrolytic effect that accompanies such current.

A circular furnace is preferred, since it exposes a minimum periphery for the loss of heat by radiation. The furnace may, how ever, be polygonal or square. Fig. 2 shows a square furnace 25 in horizontal section tl'n'ough the electrodes. A group of four electrodes 26 is shown passing through each side of the furnace. The current for this furnace is furnished by a system of transformers, the windings of which are shown in diagram. Two distinct single-phase transformers are employed, each receiving a separate current at a potential difference of, say, two thousand volts. Each of these transformers has two independent secondary windings arranged to generate an electromotive force of, say, fifty volts. 1n the figure, A B indicates the single primary winding of one transformer, A, B the first secondary winding, and second secondary winding. The single primary winding of the second transformer is marked (:1 l) and the corresponding first and second secondary windings (3' l) and (f U respectively. The current through primary (3 1) should lag one-quarter phase behind that through primary A B. The two transformers are thus equivalent toa single one receiving two-phase current. 'lerminals are lead out from the ends of the first secondary of one transformer to the end electrodes of one group of four and from the ends of the other secondary of the same transformer to the end electrodes of the opposite group of four. The intermediate electrodes of each group are connected to intermediate points of the corresponding secondary. The maximum electromotive force is thus applied to opposite electrodes; but current also flows across the furnace from each electrode to all the others. The two transformers thus furnish substantially an eight-phase current, and a fai rly uniform heatingof the furnace chargeiseflected.

I claim 1. The process of electrically heating a body of conducting material, which consists in caus- A B the IIO raams v ing different phases of a polyphase current to flow along paths which cross each other through said body, as set forth.

2. The process of electrically heating abody of conductingmaterial, which consists in causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body, as set forth.

. 3. The process of electrically heatinga body I of conducting material, which consists in causing different phases of a polyphase current to flow along paths which cross each other through said body, and progressively shifting the path of the phase of maximum electromotive force, as set fort 4:. The process of electrically heating a body of conducting material, which consists in causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body, and progressively shifting the path of the phase of maximum electromotive force, as set forth.

5. The process of electrically heating a body of conducting material, which consists in caus- 5 ing different phases of a polyphase current to flow along paths which cross each other through said body, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set 3 forth.

* 6. The process of electrically heating a body of conducting material, which consists in cansing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

7. The process of electrically heating a body 4 of conducting material. which consists in causing different phases of a polyphase current to flow along paths which cross each other through said body, progressively shifting the path of the phase of maximum electromotive force, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

paths which cross each other through said 5 body, as set forth.

10. The process of electrically heating a body of conducting material, which consists in placing the active terminals of a source of polyphase current substantially in contact with the 7 body at various points, causing different phases of the current to simultaneously flow between several of said terminals and along paths which cross each other through said body, and progressively shifting the path of the phase of 75 maximum electromotive force, as set forth.

11. The process of electrically heating a body of conducting material, which consists in placing the active terminals of a source of polyphase current substantially in contact with the 80 body at various points,causing different phases of the current to simultaneously flow between several of said terminals and along paths which cross each other through said body, and cansing each phase to traverse a path of resistance 5 corresponding to the electromotive force of that phase, as set forth.

12. The process of electrically heating a body of conducting m terial, which consists in placing the active terminals of a source of poly- 9 phase current substantially in contact with the body at various points, causing different phases of the current to simultaneously flow between several of said terminals and along paths which cross each other through said body, progress- 9 5 ively shifting the path of the phase of maximum electromotive force, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth. I00

13. The process of electrically heating a circular body of conducting material, which consists in placing the active terminalsof a source of polyphase current substantially in contact with the body at various points around its pe- 1 5 riphery, and causing different phases of the current to simultaneously flow between several of said terminals and along paths which cross each other through said body, as set forth. 1 1 0 1a. The process of electrically heating a cir- 8. The process of electrically heating abody cular body of conducting material, which conof conducting material, which consists in caussists in placing the active terminals of a source 5 ing different phases of a polyphase current to of polyphase current substantially in contact simultaneously flow along paths which cross with the body at various points around its pe- 15 each other through said body, progressively riphery, causing different phases of the curshifting the path of the phase of maximum rent to simultaneously flow between several of electromotiveforce, and causing each phase to said terminals and along paths which cross traverse a path of resistance corresponding to each other through said body, and causing the electromotive force of that phase, as set each phase totraverse a path of resistance cor- I20 forth. responding to the electromotive force of that 9. The process of electrically heating abody phase, as set forth. of conducting material, which consists in p ac- 15. The process of electricallyheating a ciring the active terminals of a source of polycular body of conducting material, which conphase current substantially in contact with the sists in placing the active terminals of a source I 5 body at various points, and causing different of polyphase current substantially in contact phases of the current to simultaneously flow with the body at various points around its pebetween several of said terminals and along riphery, causing different phases of the current to simultaneously fl ow between several of said terminals and along paths which cross each other through said body, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, with the phase of maximum electrometi ve force passing substantially along a diameter of the circular body, as set forth.

16. The process of electrically reducing a body consisting of a mixture of a compound and a reducing agent, which consists in cansing different phases of polyphase current to flow through said body or the products of reduction thereof, along paths which cross each other, as set forth.

The process of electrically reducing a body consisting of a mixture of a compound and a reducing agent, which consists in causing different phases of polyphase current to flow through said body or the products of reduction thereof, along paths which cross each other, and causing each phase to traverse a path of resistance corresponding to the electrometive force of that phase, as set forth.

18. Tie process of electrically reducing a. circular body consisting of a mixture of a compound and a reducing agent, which consists in using active termina s of a source of polyphase current, placed substantially in contact with the body or the products of reduction thereof, at various points around its periphery, and causing different phases of the current to simultaneously flow between several of said teralong paths which cross each other, as set forth.

19. The process of electrically reducing a circular body consisting of a mixture of a compound and a reducing agent, which consists in using active terminals of a source of polyphase current, placed substantially the body or the products of reduction thereof, at various points around its periphery, causing different phases of the current to simultaneously flow between several of said terminals and along paths which cross each other, and causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

20. T 1e process of producing carbids by electrically heating a body of carbid-forming materials, which consists in causing different phases of polyphase current said body or the carbid produced therefrom,

along paths which cross each other, as set forth. I

21. 1e process of producing carbids by electrically heating a body of carbid-forming materials, which consists in causing (:litferent phases of polyphase current to pass through said body or the carbid produced therefrom, along paths which cross each other, and causing each phase to traverse a path of corresponding to the electromotivc force of t rat phase, as set forth.

1e process of producing carhids by in contact with tl to pass through resistance electrically heating a circular body of carbidwhich consists in using forming materials, l

of producing carbids by electrically heating a circular body of carbidforming materials, which consists in using active terminals of a source of polyphase current placed substantially in contact with the body or the caraid produced therefrmn, at various points around its periphery, causing different phases of the current to simultaneously flow between several of sa' 1(l terminals and along paths which cross each other, and causing each phase to traverse a path of resistance correspomling to the electromotive force of that phase. as set forth.

24,-. The process of prolucing carbids by electrically heating a body of carbid-forming materials, which consists in causing different phases of polyphase current to pass through said body or the carbid produced therefrom, along paths which cross each other, and tapping off the molten carbid and feedingin fresh materials as required, as set forth.

, L5. The process of producing carbids by l electrically heating a body of carbid-forming materials, which consists in causing different phases of iiolyphase current to pass through said body or the carbid produced therefrom, i along paths which cross each other, causing l each phase to traverse a path of resistance to the elect-rmnotive force of tapping off the molten carbid and feeding in fresh materials as required, as set forth. l 2b. The process of producing carbids by electricallyheating a circular body of carbid- I formingmaterials, which consists in usingactire terminals of a source of polyphase current placed substantially in contact with the body or the carbid pl'OflIlCOd therefrom, at various points around its periphery, causing different phases of the current to sin'lultan ously fiow between several of said terminals and along paths which cross each other, and i tapping off the molten carbid and feeding in fresh materials as required, as set forth. 1 27. The process of producing carbids by electrically heating a circular body of earbidforming n'laterials, which consists in using active terminals of a source of polyphase current placed substmitially in contact with the body or the carbid produced therefrom, at various points around its periphery, causing (lllffGlPfiii phases of the current to simultaneously flow between several of said termil'ials paths which cross each other, cansi and along ing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, and tapping off the molten carbid and feeding in fresh materials as required, as set forth.

28. The process of electrically heating a body of conducting material, which consists in placing a series of electrodes substantially in contact with the body at various points around its periphery, causing difierent phases of a polyphase current to simultaneously flow between several of said terminals and along paths which cross each. other through said body, and removing and replacing each electrode as consumed, as set forth.

29. The process of electrically melting a 

